Weak signal strength causes a lot of bit errors and packet losses in the wireless environment. To address these problems associated with real-time video transmission, rate control using forward error correction (FEC) has been introduced.
Reducing packet loss in the wireless environment requires estimation of the link quality or channel condition. In particular, for the purpose of real-time video transmission, wireless channel capacity needs to be correctly estimated in real time. This is why the wireless link conditions and link quality may vary with interference, fading, multi-path effects, and mobility, and such variations may lead to a significant change in channel capacity.
In other words, the exact estimation or prediction of a wireless channel condition is critical in configuring a proper channel coding rate in order to provide enhanced video quality upon real-time video transmission.
For example, when a multimedia content stream is viewed that is transmitted through a WLAN (IEEE 802.11b) installed in the office, a channel environment may be affected by, e.g., interference caused by an access point (AP) positioned in another office, thus causing a significant distortion of the multimedia content stream.
To estimate link quality or channel condition, the wireless LAN protocol that discards packets having one or more remaining errors (MAC layer errors) has been conventionally used. In this scheme, the link quality or channel capacity is estimated using the packet error rate (PER).
Such a conventional art predicts the link quality or channel capacity using the packet error rate (PER), but not bit error rate (BER), so it suffers from low prediction accuracy and resultantly poor channel adaptivity, thus failing to guarantee desired wireless video quality.